Antenna construction with effectively extended radiator elements

ABSTRACT

An antenna construction supported atop a support tower by means of booms and cables, the cables carrying the end portions of a number of radiator elements extending laterally from an axis defined by one of the booms. The end portions of the radiator elements are turned to be disposed along the length of the cables so as to electrically enlarge the effective size of the radiating array. In one embodiment, end portions of the radiating elements constitute structurally supporting portions of the cables, whereas in another embodiment the cable comprises a unitary continuous strand. The radiators can provide either L-shaped or T-shaped end portions.

United States Patent [72] Inventor William L. Werner Cupertino, Calif. [21] Appl.No. 746,845 [22] Filed July 23, 1968 [45] Patented Nov. 2, 1971 [73] Assignee Granger Associates Palo Alto, Calif.

[54] ANTENNA CONSTRUCTION WITH EFFECTHVlELY EXTENDED RADIATOR ELEMENTS 4 Claims, 11 Drawing Figs.

[52] U.S. C1 343/792.5, 343/802, 343/884, 343/890 51 Int. c1 ..H01 11/10, H01ql/l6,l*l0lq H20 [50] Field 011 Search 343/886, 792.5, 752, 890, 858

[5 6] References Cited UNlTED STATES PATENTS 3,271,774 9/1966 Justice 343/879 x 3,373,434 3/1968 Lorenzo etal... 343/879 2,583,747 1/1952 Potter 343/890 X 2,647,211 7/1953 Smeby 343/752 3,179,943 4/1965 Buzbee 343/792.5

Primary Examiner-Herman Karl Saallbach Assistant Examiner-Wm. H. Punter A!!orney-Flehr, Hohbach, Test, Albritton & Herbert ABSTRACT: An antenna construction supported atop a support tower by means of booms and cables, the cables carrying the end portions of a number of radiator elements extending laterally from an axis defined by one of the booms. The end portions of the radiator elements are turned to be disposed along the length of the cables so as to electrically enlarge the effective size of the radiating array. In one embodiment, end portions of the radiating elements constitute structurally supporting portions of the cables, whereas in another embodiment the cable comprises a unitary continuous strand, The radiators can provide either L-shaped or T-shaped end portions.

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SHEET 1 BF 3 ENTOR WILLIAM L WERNER M41 70 fTATTORNEYS PATENTEDNBV2 I97! 3, 18,199

sum 2 0F 3 INVENTOK WILLIAM L. WERNER SI ATTORNEYS PATENTEDNUVQ I87! 3.618109 SHEET 3 OF 3 INVENTOR. WILLIAM L. WERNER 6% fizz m M 5 77W ATTORNEYS BACKGROUND-OF THE INVENTION AND OBJECTS This invention pertains to antenna structures having a Lnumber of spaced flexible radiating elements wherein their outer end portions are supported by cables strung from a support tower or mast, as shown in my copending application, for U.S. Pat. Ser. No. 648,475, now U.S. Pat. No. 3,550,140 assigned to the assignee hereof. This invention is particularly useful as a log periodic antenna with either rotatable or stationary array.

In the above general style of antenna, the supporting capability of the catenary cables for carrying the radiating array can be enhanced by permitting the cable to sag and form a more pronounced catenary. However, this reduces the available zone to be occupied by the radiating array within the reduced bounding perimeter formed by the support cables.

Accordingly, a general object of this invention is to effectively extend the radiating elements beyond the perimeter of the support cables so as to permit the catenary of the arraysupporting cables to become more pronounced without reducing the effective size of the array. Conversely, it is another object of the invention to provide an effectively enlarged array for its comparable physical size.

These and other objects of the invention will become more readily apparent from the following detailed description of preferred embodiments when considered in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION In general, an antenna system has been provided of a type including a support tower, an array of spaced flexible radiating elements, and cable means carried by the tower to support the array. The system is characterized by the fact that the outer end portions of the radiating elements are turned toextend along portions of the cable means associated with and carrying same. According to one embodiment, the cable means for supporting the array actually includes short lengths of the electrically active radiating elements incorporated into the cable structure so as to further fiinction in actively supporting the array.

According to another embodiment, the outer end portions of the radiating elements are disposed alongside and carried by the cable means whereby the cable constitutes a single elongated continuous strand. L-shaped and T-shaped end portions are also disclosed with each embodiment.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a perspective view diagrammatically showing an antenna system, according to the invention;

FIG. 2 is a diagrammatic illustration for exemplifying an object of the invention;

FIG. 3 is a plan view diagrammatically illustrating a portion of the radiating array and cable support means in the antenna system of FIG. 1;

FIG. 4 is an enlarged detail view ofmeans for supporting the end portions of radiating elements to be used in constructing an antenna system, according to FIGS. 1 and 3;

FIG. 5 is a diagram for explaining certain relationships for the end portions;

FIG. 6 diagrammatically illustrates another embodiment of means for supporting end portions of radiating elements in an antenna construction, according to FIG. 1 but modified as in FIG. 6;

FIG. 7 is an enlarged detail view of means for carrying out the construction of an antenna system, according to the embodiment shown in FIG. 6;

FIG. 8 shows, in diagrammatic plan view, an enlarged portion of another embodiment of an antenna system, according to the invention;

FIG. 9 shows an enlarged detail view of structure to be employed in carrying out the diagrammatic embodiment, according to FIG. 8;

FIG. 10 is a section view taken along the lines 10-10 of FIG. 9;and

FIG. 11 shows another embodiment of the detail shown in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The antenna system 10 shown in FIG. 1 generally comprises a support tower 11 held upright by means of equiangularly spaced guys 12 suitably anchored to the ground. Atop tower 11 there is disposed a generally triangular supporting assembly 13 which includes three radially disposed booms 14, 16, 17. A support tower extension 18 extends upwardly above the location of the root portion of each of the three booms and serves to provide an anchoring point for downwardly extending guys 19 coupled to the booms by means of bridles 21.

Feed lines 22 extend along the direction of the center boom 14 and are electrically coupled to a number of spaced flexible radiating elements 23. Feed lines 22 lead to a balun 24 carried at the base of tower 11.

Catenary cables 26, 27 support the outer end portions of the radiating elements 23.

Thus, as diagrammatically indicated in FIG. 2, the spaced radiating elements 23 form a radiating array 28 defined as the triangularly shaped area associated with reference numeral 28. This area, representing the electrically active array portion of the antenna system, has been effectively extended beyond the periphery of the supporting assembly 13. In the diagram shown in FIG. 2, the radiating array is indicated as radiating energy generally in the direction of the axis of boom 14. In order to achieve the object indicated by FIG. 2, means, as now to be described, have been employed for supporting the outer end portions of the radiating elements along portions of the cables associated with and carrying the end portions.

In FIG. 3, end portions 29 of conductive radiating elements 31 are shown which form separate sections or segments of the cable assembly 32 to actively participate in the physical support ofthe radiating array 28 formed by elements 31.

Elements 31 typically connect in a known manner (not shown) to feed lines 33 extending along the symmetrical center line 34 and, in one form of antenna of the above general type, alternate radiating elements 31 connect in succession to one or the other of the two feed lines 33.

In order to incorporate end portions 29 structurally into cable assembly 32, a structure as shown, for example, in FIG. 4 includes mechanically strong insulators 36 of conventional material, such as alumina, at each end of an end portion 29. Cable lengths 37 of conventional material, such as stranded metallic cable, form longitudinally interconnecting cable portions of the cable assembly 32. Ends of lengths 37 are looped through a coupling element 38 carried at the ends ofinsulators 36 and the loops are made fast by suitable means, such as the compression sleeve fittings 39. The other ends of insulators 36 carry a coupling element 41 (comparable to elements 38) for supporting end portions 29 between alternate successive pairs ofinsulators 36.

The outer end of radiator elements 31 comprises a strand of conductive, flexible radiator element material, such as a stranded wire cable of aluminum, alumoweld or other conventional material, further having the characteristic of mechanical strength sufficient to support the radiating array 28. The strand is trained to extend laterally outwardly of the feed lines 33 and then, by means ofajumper wire, is turned to become a portion of cable assembly 32. Accordingly, the jumper wire 42 has been electrically coupled between end portion 29 and element 31 by means of the compression sleeves 43, 44 which form the loops 46 and 47 attached to a bolt or other pin 48 carried in the end of connector element 41.

As thus arranged, each of the radiating elements 31 have been electrically end loaded in a manner which provides performance equivalent to larger arrays by forming supporting cable assembly 32 of alternating segments of conductive and nonconductive load-carrying portions, the conductive portions being part of the radiating elements.

Another embodiment of the construction detail of FIG. 4 is shown in FIG. 11 where the end portion of the radiator element is an integral continuation of the main transverse portion. Thus, a support strap 81 engages pin 82 while the ends strap are clamped to the radiator element.

The spacing between a straight phantom line 49 (FIG. and the catenary curve defined by cable assembly 32 indicates the degree of sag defined by cable assembly 32. In FIG. 5, it is demonstrated that the degree of sag for cable assembly 32 at any given point along assembly 32 serves to substantially define the length of the end-loaded portions 29 for any given radiator element 31. Thus, the spacing 51 shown in FIG. 5 is substantially equivalent to the length of that portion 29 adjacent thereto.

From the foregoing, it will be readily apparent that the radiating elements include a laterally extending major portion and a transversely extending end portion electrically coupled thereto. According to another embodiment, the major portion of the radiating elements intersect the end portions in a zone generally midway between the ends of the portions so as to form a T-type of end-loaded radiating element.

By reference to FIG. 6, therefore, a cable assembly 52 includes end-loaded portions 53 electrically coupled to radiating elements 54.

End portions 53, as mentioned above with respect to the prior embodiment, are formed by a relatively strong, conductive stranded wire cable of aluminum, Calsun bronze, or other conventional material employed for radiating elements. Insulators 56 comparable to insulators 36 are disposed at the opposite ends of portions 53 and the major portion 55 of each radiating element 54 is secured and electrically coupled substantially midway between the ends of portion 53.

This may be readily accomplished by use of a conventional compression fitting 57 and the swaged tube fitting 58.

According to another embodiment shown in FIGS. 8, 9 and 10, a radiating array 61 includes radiating elements 62 arranged in spaced-apart relation with their end portions 63 trained to extend alongside and spaced from a single continuous unitary catenary support cable 64 of suitable material, such as fiber glass rod.

Insulators 66, 67 respectively engage element 61 at an intermediate point 68 and at the tip end 69.

The compression fitting 71 forms the loop 72 for engaging the clevis 73 hung from insulator 66. Insulator 66 is, in turn,

supported by the pin 74 extending transversely through insulator 66 and coupled to the ends of the clevis like device 76. Device 76, in turn, is supported from a given location (as dictated by the antennas electrical design criteria) along cable 64 by means of the compression fitting 77.

The tip end 69 of radiator element 61 is similarly supported from cable 64 by the assembly 78.

From the foregoing, it will be readily evident that there has been provided embodiments of the invention wherein the radiating array effectively extends beyond the perimeter bounded by the supporting cable assembly. End portions of the radiating elements having a length which is dependent upon the degree of sag in the supporting cable at the point of support X of the element provide an appropriate endloading of the radiating elements,

I claim:

1. In an antenna system having a support tower, a radiating array including spaced flexible radiator elements carried by said tower and cable means substantially encircling said tower while supporting the array, a support cable comprising alternately conductive and nonconductive load-carrying lengths thereof, said conductive lengths being an electrically active portion of said array, and said nonconductive lengths serving to electrically isolate each adjacent pair of said elements.

2. In an antenna system apparatus comprising a support tower, an array of spaced flexible radiating elements, each said element being electrically isolated from those elements flanking same, cable means carried by and substantially encircling said tower to define the periphery of the array in plan view while supporting said array, the outer end portions of said elements extending along portions of the cable means, and wherein portions of said cable means include said outer end portions of the radiating elements disposed to actively support said radiating array.

3. In an antenna system according to claim 1 wherein said outer end portion of any radiating element is of an extent determined by that degree of sag of the support cable defined at the point of support for the radiating element.

4. In an antenna system according to claim 1 wherein a major portion of the radiating elements extends laterally from a vertical plane including said tower, and said end portions extend transversely of said major portions, said end portions being electrically coupled to their respective said major portions. 

1. In an antenna system having a support tower, a radiating array including spaced flexible radiator elements carried by said tower and cable means substantially encircling said tower while supporting the array, a support cable comprising alternately conductive and nonconductive load-carrying lengths thereof, said conductive lengths being an electrically active portion of said array, and said nonconductive lengths serving to electrically isolate each adjacent pair of said elements.
 2. In an antenna system apparatus comprising a support tower, an array of spaced flexible radiating elements, each said element being electrically isolated from those elements flanking same, cable means carried by and substantially encircling said tower to define the periphery of the array in plan view while supporting said array, the outer end portions of said elements extending along portions of the cable means, and wherein portions of said cable means include said outer end portions of the radiating elements disposed to actively support said radiating array.
 3. In an antenna system according to claim 1 wherein said outer end portion of any radiating element is of an extent determined by that degree of sag of the support cable defined at the point of support for the radiating element.
 4. In an antenna system according to claim 1 wherein a major portion of the radiating elements extends laterally from a vertical plane including said tower, and said end portions extend transversely of said major portions, said end portions being electrically coupled to their respective said major portions. 